When more than one electron withdrawing group is present, then the summation of the substituent constants is used to estimate or characterize the total effect of the substituents. [0213] Illustrative developing agents that are useful as developers are: [0214] wherein [0215] R20 is hydrogen, halogen, alkyl or alkoxy; [0216] R21 is a hydrogen or alkyl; [0217] R22 is hydrogen, alkyl, alkoxy or alkene